today president obama seemed a little unsure. >> al qaeda's top ranks have been hammered. but core of al qaeda in afghanistan and pakistan is on the way to defeat. al qaeda affiliates and like minded extremists still threaten our homeland, still threaten our diplomatic facilities. >> so does it really lessen the threat if the core has been hammered but affiliates have spread and actively plot against the united states? it is hard to know. one thing we know is the obama administration just stepped up the use of drones to kill terrorists. just how effective are they? barbara starr with an investigation. >> reporter: within hours of learning al qaeda in yemen was planning a major attack president obama increased drone operations in a frantic effort to find the terrorists. operations have been cut back but now the gloves were off as senior administration official tells cnn. national security trumped everything else. in the last week and a half five drone attacks over yemen. about one-third of all attacks so far all this year. drones remain controversial. president obama insist